The day after Malaysia Airlines flight MH 17 was shot down in Ukraine, members of the tight-knit HIV/AIDS community are mourning the loss of roughly 100 researchers, who were killed en route to the International Aids Society conference in Melbourne, Australia.

Although the IAS did not confirm the number of conference attendees on the plane, President Barack Obama told reporters today that nearly 100 AIDS/HIV researchers and scientists were on board MH 17 when it was shot down.

The conference will continue “in recognition of our colleagues' dedication to the fight against HIV/AIDS,” organizers said, but attendees will have “opportunities to reflect and remember those we have lost.”

“We know that it's really what they would like us to do,” Nobel laureate and IAS president Dr. Francoise Barre-Sinoussi told reporters.

Among the passengers aboard MH 17 was Dr. Joep Lange, a former president of the IAS from the Netherlands, who has been a leading expert in the field of HIV/AIDS since the 1980s.

Chris Beyrer, IAS president-elect, said Thursday that if Lange perished on the flight, “the HIV/AIDS movement has truly lost a giant.”

“In this incredible sad and sensitive time, the IAS stands with its international family and sends condolences to the loved ones of those who have been lost in this tragedy,” Beyrer told reporters.

Lange’s partner, HIV/AIDS researcher Jacqueline van Tongeren, was also a passenger on the downed plane.

Lange’s longtime friend and colleague, Dr. Michael Merson, said the Dutch scientist was one of the first to use antiretroviral drugs to fight HIV and became an expert in the treatment.

“He really was very special and if you were to come up with the leaders in AIDS [since] the pandemic began in 1981,” said Merson, who is director of the Duke Global Health Institute. “You’d put him among the top five leaders.”

Merson said in the 22 years he knew Lange, the scientist started numerous initiatives to combat the HIV/AIDS in Europe and Africa. After drugs to control HIV started to gain traction in the mid 1990s, Lange focused his efforts on global health initiatives to get the medication to anyone who needed it.

"His second home was Africa, he worked in east Africa and Asia and Latin America," said Merson. "He would stay it like it is. He was an outstanding scientists and fierce advocate."

Merson said he has no doubt that Lange’s work will continue.

“There’s no question there will be loss and there will be some things that slow down,” said Merson. “But he has great colleagues and dedicated scientists and researchers that are in his institute in Amsterdam. He knows that they want him to continue. “

World Health Organization spokesperson Glenn Thomas was also aboard MH 17 to the conference, the organization confirmed.

“His twin sister says he died doing what he loved,” WHO said in a statement. “Glenn will be remembered for his ready laugh and his passion for public health.”